With continuous increase of the population density, the living area occupied by human beings becomes larger and larger. However, since resources and space are finite, whether the furniture and appliances occupy a large space and whether the functions thereof are diversified become the main points of consideration for home decoration design at present. Traditional chairs occupy a larger spatial size in both horizontal direction and vertical direction. When larger space is needed at home or in office, the traditional chairs must be moved out, causing inconvenience. Further, traditional chairs do not possess the function of adjusting the backrest angle. When the backrest of the chair needs to be adjusted for a better rest or an emergent patient needs to lie flatly in a transporting process, a common chair cannot meet such demands.
Therefore, a folding seat which is adjustable in backrest angle is needed. If necessary, the folding seat can be used as a stretcher by adjusting the angle between the backrest and the seating panel to 180 degrees.